Japan is an island, and by August 1945, the U.S. Navy had overwhelmingly crushed its Japanese counterpart. The U.S. Navy could have imposed a tight blockade around Japan's home islands, allowed a minimum of food, medicine, etc. in for humanitarian purposes, and simply waited for Japan to capitulate. This option would have saved hundreds of thousands of civilian lives and allowed the United States to have avoided stooping to the low regard for civilian life that its enemies exhibited on so many occasions.

However, a naval blockade of Japan would not have fulfilled perhaps the real purpose of the atomic bombs: demonstrating the power of the new weapon to a then ally and likely future enemy--the Soviet Union. President Harry Truman delayed testing of the atomic bomb until the Potsdam Conference with Winston Churchill and Soviet leader Joseph Stalin, and comments were made at the conference that Truman wore the bomb ostentatiously on his hip to intimidate Stalin. However, it was morally questionable to drop powerful bombs on Japanese civilians, killing hundreds of thousands, merely to impress a possible future enemy with U.S. technology and power.